Hypoplastic Left Heart Syndrome

Diagnosis

To diagnose hypoplastic left heart syndrome (HLHS), a healthcare professional examines the baby and listens for a heart murmur, which is caused by the rushing flow of blood through the heart. Early detection is crucial, as HLHS is a serious congenital heart defect that requires immediate medical attention after birth.

Tests

Several tests may be used to identify HLHS before or after birth:

• Pregnancy ultrasound: A routine second-trimester ultrasound can often detect HLHS while the baby is still in the womb.

• Echocardiogram: This test uses sound waves to create images of the heart and assess how blood flows through it. It helps confirm HLHS by showing a smaller lower left heart chamber, underdeveloped heart valves, and a smaller aorta.

If HLHS is suspected before birth, healthcare professionals usually recommend delivering the baby at a hospital equipped with a cardiac surgery center for immediate care.

Treatment

Babies born with hypoplastic left heart syndrome require urgent treatment that may include surgery or a heart transplant. Medicines and supportive therapies are used to stabilize the baby before major procedures.

Medications

Alprostadil (Prostin VR Pediatric) is commonly given to keep the ductus arteriosus open after birth. This blood vessel, which usually closes soon after delivery, must remain open in babies with HLHS to allow blood flow to the body.

Therapies

Before surgery or transplant, babies may receive supportive care such as:

• Breathing assistance using a ventilator

• Intravenous (IV) fluids to maintain hydration and nutrition

• Feeding through a tube if the baby has trouble feeding or tires easily while feeding

Surgery or other procedures

Most children with HLHS undergo several surgeries in stages to improve blood flow and heart function.

Atrial septostomy: This procedure uses a catheter and balloon to create or widen an opening between the heart’s upper chambers. It allows better blood flow between the chambers if the natural opening (foramen ovale) is too small or has closed.

Norwood procedure: Usually performed within the first two weeks of life, this surgery reconstructs the aorta and connects it to the right lower heart chamber. A shunt is added to supply blood to the lungs. There are variations of this procedure, including hybrid approaches that use stents and bands to control blood flow. After surgery, the baby’s skin may still appear blue or gray because of mixed oxygen-rich and oxygen-poor blood, but survival rates improve significantly after this stage.

Bidirectional Glenn procedure: Performed at around 4 to 6 months of age, this surgery removes the shunt and connects the superior vena cava (the vein carrying blood from the upper body) directly to the pulmonary artery. This reduces the workload on the right heart chamber and improves oxygen levels in the blood.

Fontan procedure: Typically done between 3 and 4 years of age, this final stage connects the inferior vena cava (which carries blood from the lower body) to the pulmonary arteries. After this surgery, oxygen-poor blood flows directly to the lungs, and oxygen-rich blood is pumped efficiently throughout the body.

Heart transplant: In some cases, babies with HLHS may require a heart transplant. Those who receive a transplant must take lifelong medications to prevent organ rejection.

Follow-up care

After surgery or a heart transplant, lifelong follow-up with a cardiologist specializing in congenital heart disease is essential. Children may need additional medicines or procedures to manage complications. Some may also require antibiotics before certain dental or medical procedures to prevent infections. Activity restrictions may apply depending on the child’s condition.

Follow-up care for adults

Adults who were born with hypoplastic left heart syndrome need continuous care from cardiologists trained in adult congenital heart disease. Medical advances have allowed many children with HLHS to reach adulthood, but long-term health effects are still being studied.

Adults with HLHS should have regular checkups to monitor heart function and discuss pregnancy risks or birth control options with healthcare professionals. Pregnancy can pose risks such as heart complications, miscarriage, or having a baby with a congenital heart defect.